1. Field of the Invention
The present invention relates to a medical image forming method and a forming apparatus of the same, in particular, to a forming method of clearly readable medical images of the surfaces of living tissues (such as the mouth, esophagus, and stomach walls) of a human body with sublimating dyes (thermal transfer dies) through an endoscope or the like.
2. Description of the Related Art
As the needs of full-color prints increase, a variety of thermal transfer techniques have been developed. As an example of these techniques, thermosensitive sublimating transfer technique for transferring sublimating dyes as color materials held on a base film such as a polyester film to an image receiving sheet on which a synthetic resin such as polyester is coated is known. In this technique, the amount of energy supplied to a heating device (for example, a thermal head and a laser), which heats the rear surface of a thermal transfer sheet, is adjusted in accordance with electric signals (image signals) received from an endoscope or the like, thereby controlling the transferring amount of dyes to an image receiving sheet. When three types of dyes (three primary colors of yellow, magenta, and cyan) are used and the thermal transfer process is performed three times, a multi-tone full color image can be obtained.
In this thermal transfer technique, since the thermal transfer efficiency depends on the color materials, when image signals are converted into thermal energy to be supplied to the heating device, compensations for these color materials are performed.
In conventional image forming apparatuses according to this technique, the amount of thermal energy of each of the three primary colors is adjusted and their tones are compensated so that an achromatic color image can be formed in accordance with an achromatic color signal being input.
When images of the surfaces of living tissues such as the mouth, esophagus, and stomach walls are formed, red color is much more frequently used than other colors due to the property of the living tissues. Moreover, in the clinical situation, medical doctors tend to diagnose the diseases of patients based on delicate changes of red color. Thus, the reproduction of red color is very important.
However, in images obtained by the conventional tone compensations, the low density region of red color was not satisfactory. Therefore, the medical doctors could not precisely diagnose diseases of their patients with these images.